People seem to underestimate complications of the flu.

What does the CDC say?

https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm

Similarities: Both COVID-19 and flu can result in complications, including:

Pneumonia

Respiratory failure

Acute respiratory distress syndrome (fluid in the lungs)

Sepsis (a life-threatening illness caused by the body’s extreme response to an infection)

Cardiac injury (for example, heart attacks and stroke)

Multiple-organ failure (respiratory failure, kidney failure, shock)

Worsening of chronic medical conditions (involving the lungs, heart, or nervous system or diabetes)

Inflammation of the heart, brain, or muscle tissues

Secondary infections (bacterial or fungal infections that can occur in people who have already been infected with flu or COVID-19)

That may be so but feels tangential to my point. Perhaps address the parent to my comment? They're the one who believes that this is a symptom not present in the flu.

It's worth considering that the treatment could also be the cause of the blood clotting though. Do you agree?

> It's worth considering that the treatment could also be the cause of the blood clotting though. Do you agree?

No, the vaccine, being made from the virus, can give some side effects. Usually, these are the same but lesser side effects as the virus it self. This applies in this case too:

From [0] and [1]:

> There would be around 107 additional cases of thrombocytopenia—a form of rare blood clotting—and 66 cases of venous blood clots for every 10 million having their first AstraZeneca shot, according to the data, versus around 934 and 12,614 extra cases respectively for the same number of people after a Covid-19 infection.

191 times more likely to get venous blood clots from covid than from (in this study) Pfizer.

[0] https://www.forbes.com/sites/roberthart/2021/08/27/covid-inf...

[1] https://www.bmj.com/content/374/bmj.n1931